The present invention relates to a device for coupling a cable of a lifting device to a prefabricated component to be lifted or to be transported, especially to a precast concrete component, the device comprising a receiving member for the cable that is supported at the surface of the prefabricated component with a fastener in a rotatable manner.
A known device of the aforementioned kind is described in European document 0 161 652 and is comprised of an ring screw that is screwed into the prefabricated (precast) concrete component and has an annular element that is rotatable relative to the threaded bolt screwed into the prefabricated concrete component. At the outer end of the threaded bolt a securing member is provided that supports the annular element. Due to its rotatability the annular element is adaptable to pulling action at a slant exerted by the pulling or lifting device without the threaded bolt being rotated within the precast component. This substantially prevents overloading by angular pulling forces. The threaded bolt which is fixedly connected within the precast concrete component acts as a pulling anchor and is screwed into a sleeve cast into the component and above which a support plate is provided which is a unitary part of the threaded bolt. The ring screw which is rotatable about 360.degree. has a transverse opening above the threaded bolt which is engaged by a part of the lifting device, for example, an intermediate member in the form of a massive ring or a cable loop.
It is disadvantageous in this design that the point of action of the lifting forces when exerted at an angle is positioned at a relatively great distance from the surface of the precast component to be moved so that the forces acting at an angle exert considerable bending forces on parts of the device, for example, on the ring screw, the threaded bolt, and the threaded sleeve which upon transverse load may even result in breakage of the threaded sleeve or of the fastener. The known device therefore must be dimensioned correspondingly larger (stronger) for reasons of safety. Furthermore, it is disadvantageous that the oval annular element, embodied in the form of a handle, is subjected, due to its oval receiving opening which, relative to the precast component surface, is positioned relatively high above the component surface for receiving the intermediate member or the cable loop, to pulling, bending, and transverse forces depending on the point of action of the lifting force so that this component must also be dimensioned relatively large (strong).
It is therefore an object of the present invention to provide a device of the aforementioned kind with which the disadvantages of the known device can be avoided, in which the loading with respect to bending especially of the pulling anchor which is screwed into the threaded sleeve cast into the component is reduced in an optimal manner when slanted or transverse pulling forces are generated, and which is designed such that during lifting of the load the forces have the smallest possible distance to the surface of the component to be lifted, whereby it is also desired to avoid a single point of action of the lifting force in the pulling direction at the device.